Numerical Analysis of the Catalytic Combustion of Premixed Methane/Air Mixtures in Microtubes

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2008J. Zhong
Abstract
The combustion characteristics and extinction limits for the catalytic combustion of a methane/air mixture in a microtube are investigated computationally using the commercial CFD code FLUENT coupled to an external subroutine DETCHEM.
The effects of the microtube dimensions, conductivities of wall materials, external heat losses and flow velocity on the combustion stability, are also studied.
The numerical model is set as either adiabatic or non-adiabatic with a fixed exterior heat transfer coefficient.
Numerical results indicate that thermal conductivity and wall thickness are vital to preheat the methane/air mixture through the conducting wall.
Two types of extinction occur, i.e., thermal quenching and blow out.
These extinction limits are characterized by wall surface temperature in the microtube and the ratioof Pt(s)/O(s).
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Investigation of virulence genes in clinical isolates of Yersinia enterocolitica

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2008Haoxuan Zheng
Abstract
In this study, we aimed to investigate the distribution of virulence genes in clinical isolates of pathogenic Yersinia enterocolitica.
Two thousand six hundred stool samples were collected from 2600 patients with diarrhea, and were tested using the culture method and real-time PCR.
Then, all isolates of pathogenic Y. enterocolitica cultured from the culture method were examined for virulence genes (inv, ail, ystA, ystB, ystC, yadA, virF) by PCR and for the presence of plasmid by four phenotypic tests.
As a result, 160 pathogenic strains were successfully detected by the culture method, including bio/serotype 1A/unknown (4), 1B/unknown (8), 2/O:9 (39), 2/unknown (7), 3/O:3 (22), 3/unknown (6), 4/O:3 (55), 4/unknown (10) and 5/unknown (9).
The positive rate of virulence genes tested in 160 isolates was inv (100%), ail (94%), ystA (93%), ystB (7.5%), ystC (5%), yadA (89%) and virF (82%) while the phenotypic test included autoagglutination (87%), binding of crystal violet (89%), calcium-dependent growth (74%) and Congo red absorption (78%), respectively.
Finally, we found that not all pathogenic Y. enterocolitica necessarily carry all traditional virulence genes in both chromosomes and plasmids to cause illness.
Perhaps, some of them, lacking some traditional virulence genes, contain other unknown virulence markers that interact with each other and play an important role in the diverse pathogenesis of pathogenic Y. enterocolitica.
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JOURNAL OF PINEAL RESEARCH, Issue 1 2001Akihiko WakatsukiOur objective was to investigate the effects of melatonin on the free radical-induced oxidative damage to mitochondria in fetal rat brain.
Female Wistar rats on day 19 of pregnancy were used.
Melatonin (10 mg/kg) or vehicle (control) was injected intraperitoneally 60 min prior to laparotomy for removal of the fetuses.
The mitochondrial fraction was isolated from the fetal rat brain of each group.
Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured.
As indicators of mitochondrial respiratory activity, we determined the respiratory control index (RCI) and the adenosine 5-diphosphate/oxygen (ADP/O) ratio in the presence and absence of 2.5 ,M hypoxanthine and 0.02 units/mL xanthine oxidase.
Mitochondrial lipid peroxidation was determined by measuring the concentration of thiobarbituric acid reactive substances in fetal brain mitochondria in the presence or absence of 2.5 ,M hypoxanthine, 0.02 units/mL xanthine oxidase, and 50 ,M FeSO4.
The free radical-induced rates of inhibition of mitochondrial RCI and the ADP/O ratio were both significantly lower in the fetal rat brains treated with melatonin compared with those of the controls (RCI, 44.25±15.02% vs.
25.18±5.86%, P<0.01; ADP/O ratio, 50.74±23.05% vs.
13.90±7.80%, P<0.001).
The mitochondrial lipid peroxidation induced by free radicals was significantly reduced in the melatonin-treated group compared with the controls (484.2±147.2% vs.
337.6±61.0%, P<0.01).
Pretreatment with melatonin significantly increased the activity of GSH-Px (20.35±5.27 to 28.93±11.01 mU/min mg,1 protein, P<0.05) in fetal rat brain mitochondria, but the activity of SOD did not change significantly.
Results indicate that the administration of melatonin to the pregnant rat may prevent the free radical-induced oxidative mitochondrial damage to fetal rat brain by a direct antioxidant effect and the activation of GSH-Px.
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Identification of arid phases during the last 50,cal. ka BP from the Fuentillejo maar-lacustrine record (Campo de Calatrava Volcanic Field, Spain),

Dentistry/O & M; Dermatology/plastic surgery

JOURNAL OF FOOD SCIENCE, Issue 9 2006A.V. Schirack
ABSTRACT:, Microwave blanching of peanuts has been explored as an alternative to conventional oven methods based on its speed of operation, energy savings, and efficiency of process control.
Although processing times can be greatly reduced, the occurrence of stale/floral and ashy off-flavors has been reported at high process temperatures.
This study examined the chemical compounds responsible for this off-flavor using solvent extraction/solvent assisted flavor evaporation (SAFE), gas chromatography-olfactometry (GC/O), gas chromatography-mass spectrometry (GC/MS), and aroma extract dilution analysis (AEDA).
Select compounds were quantified based on AEDA results using SAFE and GC/MS.
Quantification, threshold testing, and analysis of model systems revealed increased formation of guaiacol and phenylacetaldehyde in the off-flavored peanuts, which resulted in the burnt and stale/floral flavors noted by a trained panel.
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G,, that interacts with adenylyl cyclase in opioid tolerance originates from a Gs protein

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2004Shin'Ichiro Satake
Abstract
A major subtype of glutamate receptors, AMPA receptors (AMPARs), are generally thought to mediate excitation at mammalian central synapses via the ionotropic action of ligand-gated channel opening.
It has recently emerged, however, that synaptic activation of AMPARs by glutamate released from the climbing fibre input elicits not only postsynaptic excitation but also presynaptic inhibition of GABAergic transmission onto Purkinje cells in the cerebellar cortex.
Although presynaptic inhibition is critical for information processing at central synapses, the molecular mechanisms by which AMPARs take part in such actions are not known.
This study therefore aimed at further examining the properties of AMPAR-mediated presynaptic inhibition at GABAergic synapses in the rat cerebellum.
Our data provide evidence that the climbing fibre-induced inhibition of GABA release from interneurons depends on AMPAR-mediated activation of GTP-binding proteins coupled with down-regulation of presynaptic voltage-dependent Ca2+ channels.
A Gi/o -protein inhibitor, N-ethylmaleimide, selectively abolished the AMPAR-mediated presynaptic inhibition at cerebellar GABAergic synapses but did not affect AMPAR-mediated excitatory actions on Purkinje cells.
Furthermore, both Gi/o -coupled receptor agonists, baclofen and DCG-IV, and the P/Q-type calcium channel blocker ,-agatoxin IVA markedly occluded the AMPAR-mediated inhibition of GABAergic transmission.
Conversely, AMPAR activation inhibited action potential-triggered Ca2+ influx into individual axonal boutons of cerebellar GABAergic interneurons.
By suppressing the inhibitory inputs to Purkinje cells, the AMPAR-mediated presynaptic inhibition could thus provide a feed-forward mechanism for the information flow from the cerebellar cortex.
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EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003Joanne L. Leaney
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels are found in neurons, atrial myocytes and neuroendocrine cells.
A characteristic feature is their activation by stimulation of Gi/o -coupled receptors.
In central neurons, for example, they are activated by adenosine and GABA and, as such, they play an important role in neurotransmitter-mediated regulation of membrane excitability.
The channels are tetrameric assemblies of Kir3.x subunits (Kir3.1,3.4 plus splice variants).
In this study I have attempted to identify the channel subunits which contribute to the native GIRK current recorded from primary cultured rat hippocampal pyramidal neurons.
Reverse transcriptase,polymerase chain reaction revealed the expression of mRNA for Kir3.1, 3.2A, 3.2C and 3.3 subunits and confocal immunofluorescence microscopy was used to investigate their expression patterns.
Diffuse staining was observed on both cell somata and dendrites for Kir3.1 and Kir3.2A yet that for Kir3.2C was weaker and punctate.
Whole-cell patch clamp recordings were used to record GIRK currents from hippocampal pyramidal neurons which were identified on the basis of inward rectification, dependence of reversal potential on external potassium concentration and sensitivity to tertiapin.
The GIRK currents were enhanced by the stimulation of a number of Gi/o -coupled receptors and were inhibited by pertussis toxin.
In order to ascertain which Kir3.x subunits were responsible for the native GIRK current I compared the properties with those of the cloned Kir3.1 + 3.2A and Kir3.1 + 3.2C channels heterologously expressed in HEK293 cells.
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Coupling of Canine Serotonin 5-HT1B and 5-HT1D Receptor Subtypes to the Formation of Inositol Phosphates by Dual Interactions with Endogenous Gi/o and Recombinant G,15 Proteins

THE JOURNAL OF PHYSIOLOGY, Issue 2 2007Toshihide Tabata
Adenosine receptors (ARs) are G protein-coupled receptors (GPCRs) mediating the neuromodulatory actions of adenosine that influence emotional, cognitive, motor, and other functions in the central nervous system (CNS).
Previous studies show complex formation between ARs and metabotropic glutamate receptors (mGluRs) in heterologous systems and close colocalization of ARs and mGluRs in several central neurons.
Here we explored the possibility of intimate functional interplay between Gi/o protein-coupled A1 -subtype AR (A1R) and type-1 mGluR (mGluR1) naturally occurring in cerebellar Purkinje cells.
Using a perforated-patch voltage-clamp technique, we found that both synthetic and endogenous agonists for A1R induced continuous depression of a mGluR1-coupled inward current.
A1R agonists also depressed mGluR1-coupled intracellular Ca2+ mobilization monitored by fluorometry.
A1R indeed mediated this depression because genetic depletion of A1R abolished it.
Surprisingly, A1R agonist-induced depression persisted after blockade of Gi/o protein.
The depression appeared to involve neither the cAMP-protein kinase A cascade downstream of the alpha subunits of Gi/o and Gs proteins, nor cytoplasmic Ca2+ that is suggested to be regulated by the beta-gamma subunit complex of Gi/o protein.
Moreover, A1R did not appear to affect Gq protein which mediates the mGluR1-coupled responses.
These findings suggest that A1R modulates mGluR1 signalling without the aid of the major G proteins.
In this respect, the A1R-mediated depression of mGluR1 signalling shown here is clearly distinguished from the A1R-mediated neuronal responses described so far.
These findings demonstrate a novel neuromodulatory action of adenosine in central neurons.
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ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010Vratislav Langer
In the crystal structures of the title compounds, C11H9FN2O, (I), and C13H12FNO4, (II), the molecules are joined pairwise via different hydrogen bonds and the constituent pairs are crosslinked by weak C,H...O hydrogen bonds.
The basic structural motif in (I), which is partially disordered, comprises pairs of molecules arranged in an antiparallel fashion which enables C,H...N[triple-bond]C interactions.
The pairs of molecules are crosslinked by two weak C,H...O hydrogen bonds.
The constituent pair in (II) is formed by intramolecular bifurcated C,H...O/O, and combined inter- and intramolecular N,H...O hydrogen bonds.
In both structures, F atoms form weak C,F...H,C interactions with the H atoms of the two neighbouring methyl groups, the H...F separations being 2.59/2.80 and 2.63/2.71,Å in (I) and (II), respectively.
The bond orders in the molecules, estimated using the natural bond orbitals (NBO) formalism, correlate with the changes in bond lengths.
Deviations from the ideal molecular geometry are explained by the concept of non-equivalent hybrid orbitals.
The existence of possible conformers of (I) and (II) is analysed by molecular calculations at the B3LYP/6,31+G** level of theory.
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Pressure and gas composition effects on the operation of the pulsed flame photometric detector

ISRAEL JOURNAL OF CHEMISTRY, Issue 2 2001Gad Frishman
The effect of pressure and hydrogen/oxygen ratioof a burning gas mixture on pulsed flame emission time-dependence was investigated in the range of 0.1,5 atm using a specially designed pulsed flame photometric detector (PFPD).
We studied the pressure and gas composition effect on the pulsed flame delayed light emission of sulfur, phosphorus, and nitrogen-containing organic compounds.
The optimal pressure conditions for nitrogen detection, intensity, and emission time delay was found to be 0.4 bar, at which the detection sensitivity could be improved by a factor of 2.
For phosphorus, the optimal pressure obtained was 1.3 bar with 40% sensitivity improvement (compared with 1 bar).
In the case of sulfur detection, two emission maxima were obtained, at 1.1 and 0.6 bar, at H/O ratioof 5.
Increasing the H/O ratio resulted in the appearance of only one peak at 1 bar, and enhancement of the sensitivity by a factor of 2.4 at H/O ratioof 10.3. From the analytical point of view, we found that emission intensity is practically unchanged by the pressure and the H/O ratio for all three elements investigated in the range of 0.8,1.1 bar and H/Oof 5,6.
Thus, in addition to excellent sensitivity and improved selectivity, the PFPD can be applied under a variety of atmospheric pressure conditions in field environmental applications.
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ELECTROANALYSIS, Issue 13-14 2006Jan Langmaier
Abstract
Voltammetric measurements of heparin at a rotating glassy carbon (GC) electrode coated with a polyvinylchloride membrane are reported.
A spin-coating technique is used to prepare thin membranes (20,40,,m) with a composition of 25% (w/w) PVC, 1,1,-dimethylferrocene as a reference electron donor for the GC|membrane interface, nitrophenyl octyl ether (o -NPOE) or bis(2-ethylhexyl) sebacate (DOS) as a plasticizer, and hexadecyltrimethylammonium tetrakis(4-chlorophenyl) borate (HTMATPBCl) or tridodecylmethylammonium tetrakis(4-chlorophenyl) borate (TDMATPBCl) as a background electrolyte.
It is shown that the electrodes coated with either the HTMA+/o -NPOE (DOS) or TDMA+/o -NPOE (DOS) membrane provide a comparable amperometric response towards heparin (1,10,U mL,1) in the aqueous solution of 0.1,M LiCl.
However, only the membranes formulated with TDMATPBCl can be used for an amperometric assay of heparin in human blood plasma with a detection limit of 0.2,U mL,1.
Effects of membrane composition, heparin concentration, rotation speed and sweep rate on the voltammetric behavior of heparin provide some insight into the sensing mechanism.
Theoretical analysis of the amperometric response is outlined, and the numeric simulation of the voltammetric behavior is presented.
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Recent Developments and Applications of Haptic Devices

COMPUTER GRAPHICS FORUM, Issue 2 2003S. D. Laycock
Abstract
Over recent years a variety of haptic feedback devices have been developed and are being used in a number of important applications.
They range from joysticks used in the entertainment industry to specialised devices used in medical applications.
This paper will describe the recent developments of these devices and show how they have been applied.
It also examines how haptic feedback has been combined with visual display devices, such as virtual reality walls and workbenches, in order to improve the immersive experience.
ACM CSS: H.5.2 Information Interfaces and Presentation,Haptic I/O; I.3.8 Computer Graphics,Applications; I.6 Simulation and Modelling,Applications
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EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2002Mireille Bonnard
Abstract
The aim of this study was to determine the relative involvement of the corticospinal (CS) pathway in voluntarily controlled walking compared to unconstrained walking.
In the voluntarily controlled walking condition, subjects had to walk at the same speed as in unconstrained walking with a mechanical constraint, which is known to affect specifically the upper-leg muscles.
The motor cortex was activated transcranially using a focal magnetic stimulation coil in order to elicit motor evoked potentials (MEPs) in the rectus femoris (RF) and the biceps femoris (BF).
The magnetic stimulation was delivered at the end of the swing (at 90% of the cycle duration), when the EMG backgrounds were similar in the two experimental conditions.
For each subject in each condition, MEPs were measured for several stimulus intensities in order to establish the input/output (I/O) curve (MEPs amplitude plotted against stimulus strength).
The results showed a significant increase in the MEPs amplitude of both the RF and BF in voluntarily controlled walking compared to unconstrained walking, which is the first evidence of cofacilitation of MEPs in antagonist upper-leg muscles during human gait.
In conclusion, although a lot of studies have emphasized a privileged input of the corticospinal pathway to the distal lower-leg muscles, this study shows that, if a locomotory task requires fine control of the proximal upper-leg muscles, a selective facilitation of MEPs is observed in these muscles.
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INDOOR AIR, Issue 2 2010B. Pekey
Abstract, This study presents indoor/outdoor PM2.5 and PM10 concentrations measured during winter and summer in 15 homes in Kocaeli, which is one of the most industrialized areas in Turkey.
Indoor and outdoor PM2.5 and PM10 mass concentrations and elemental composition were determined using an X-ray fluorescence spectrometer.
Quantitative information was obtained on mass concentrations and other characteristics such as seasonal variation, indoor/outdoor (I/O) ratio, PM2.5/PM10 ratio, correlations and sources.
Average indoor and outdoor PM2.5 concentrations were 29.8 and 23.5 ,g/m3 for the summer period, and 24.4 and 21.8 ,g/m3 for the winter period, respectively.
Average indoor and outdoor PM10 concentrations were 45.5 and 59.9 ,g/m3 for the summer period, and 56.9 and 102.3 ,g/m3 for the winter period, respectively.
A varimax rotated factor analysis (FA) was performed separately on indoor and outdoor datasets in an effort to identify possible heavy metal sources of PM2.5 and PM10 particle fractions.
FA of outdoor data produced source categories comprising polluted soil, industry, motor vehicles, and fossil fuel combustion for both PM fractions, while source categories determined for indoor data for both PM2.5 and PM10 comprised industry, polluted soil, motor vehicles, and smoking, with an additional source category of cooking activities detected for the PM2.5 fraction.
Practical Implications
In buildings close to industrial areas or traffic arteries, outdoor sources may have an important effect on indoor air pollution.
Therefore, indoor and outdoor investigations should be conducted simultaneously to assess the relationship between indoor and outdoor pollution.
This study presents the simultaneous measurement of PM fractions (PM2.5 and PM10) and their elemental compositions to determine the sources of respirable PM and the heavy metals bound to these particles in indoor air.
Factor analysis of indoor data indicated that the contribution of outdoor pollutant sources to indoor pollution was about 70%, making these sources the most significant for indoor heavy metal pollution, wheras other sources of indoor pollution included smoking and cooking activities.
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